I need update in my phone

Go to Settings ➜ General ➜ Software Update. click here ➡️ Update your iPhone or iPad - Apple Support

Do note an iPhone 5S cannot update past iOS 12.5.7

If your iPhone is running iOS 10.3.3 or 10.3.4 and is not getting any further updates in Settings ➜ General ➜ Software Update, then it's probably an iPhone 5 or 5C not a 5S, and cannot update beyond 10.3.3 / 10.3.4

oops, did not see the previous post.

Your iPhone 5s can only update as far as iOS 12.5.7

Here are two different ways to ensure the highest iOS that your device will support is on your device.

Update your iPhone, iPad, or iPod touch wirelessly. Click here --> Update your iPhone or iPad - Apple Support

Here are instructions about how to update your iPhone, iPad, or iPod touch with the Finder on a Mac computer --> Update your iPhone, iPad, or iPod touch with the Finder - Apple Support